I am creating an application in VB.NET 4.7.2 with Visual Studio 2019.
The user must authenticate himself with OpenID Connect.
I already downloaded the IdentityModel Package with the NuGet Package Manager and tried to code the authentication method.
Before First Step: Import libraries
Imports System.Net
Imports IdentityModel.Client
Imports System.Threading.Tasks
First Step: Token Request Data
Function Get_Token As String()
Dim request As TokenRequest = New TokenRequest
request.Address = "https://demo.identityserver.io/connect/token"
request.GrantType = "custom"
request.ClientId = "ClientID"
request.Parameters.Add("parameter1", "value1")
request.Parameters.Add("parameter2", "value2")
Second Step: Call an asynchronous function for the request for the token. I must use an asynchronous function, because the response of the function RequestTokenAsync has Task(Of TokenResponse) as type. My problem here:
Is this the right way? How do I call the async. function, so that the return variable response can be evaluated in the calling function?
Call AsyncCall(request)
The asynchronous function: Does not work and gives the error NullReferenceException
Async Function AsyncCall(rqst As TokenRequest) As Task(Of TokenResponse)
Dim client As Http.HttpClient = New Http.HttpClient()
Dim response As TokenResponse = Await client.RequestTokenAsync(rqst)
Return response
End Function
The asynchronous function returns the variable response to the function Get_Token and the variable is evaluated further:
Third Step: Evaluation of response
Even though the asynchronous function had "Return response" in order to return the variable response to the calling function, the calling function does not recognize response, how can I return the variable response properly?
Get_Token = response.AccessToken
End Function
Can you please help me, or show me any direction?
The IdentityModel coding model changed a while back as follows:
Don't use TokenClient - use HttpClient instead
Use the RequestTokenAsync extension method --> You are doing this already
Also use the TokenRequest object --> You are doing this already
Here is the expected usage
Related
I want to create a post method to read data from body sent by Authorize.Net webhook using VB.Net and i'm new in VB.Net can someone please assist how to read data from body in a Post type method.
To send/receive HTTP requests/responses, typically you would use the HttpClient class (documentation). Specifically in this case you would:
Call the PostAsync method (documentation) to submit the request
Check the response's StatusCode (documentation) to verify that a successful response was returned (presumably an OK - 200 status)
If a successful response was returned, get the response's Content (documentation)
Here is a function (untested) that should get you going in the right direction:
Imports System.Net
Imports System.Net.Http
Imports System.Threading.Tasks
Imports Newtonsoft.Json
Imports System.Text
'...
Private Async Function SendPost(url As String, data As Object) As Task(Of String)
Dim body = String.Empty
Using client = New HttpClient
Dim content As New StringContent(JsonConvert.SerializeObject(data), Encoding.UTF8, "application/json")
Dim response = Await client.PostAsync(url, content)
If (response.StatusCode = HttpStatusCode.OK) Then
body = Await response.Content.ReadAsStringAsync()
End If
End Using
Return body
End Function
I have a VB.NET function as below:
Public Shared Async Function GetIdDoc() As Task(Of String)
Dim result As String = ""
'Dim Uri As String = "http://localhost:53917/api/Documenti/GetNextIdDocumenti"
Dim Uri As String = apiUri & ApiEndPoints.GetNextIdDocumenti
Using client = New HttpClient()
Using response = Await client.GetAsync(Uri)
If response.IsSuccessStatusCode Then
Dim DocumentiIDJsonString = Await response.Content.ReadAsStringAsync()
result = DocumentiIDJsonString.ToString()
End If
End Using
End Using
Return result
End Function
I'm trying to return the Document ID from the DB but I'm getting
System.Threading.Tasks.Task`1[System.String]
Where actually it should return "2". Please help me on this: what am I doing wrong with this function?
Update
here is the function called:
txtIDDoc_Detail.Text = ApiData.GetIdDoc().ToString()
But inside the textbox I'm getting the above text. thanks.
I'm from C# but should work the same. In newer .Net Versions (>= 4.5) async/await is implemented. So if a method is marked as async and returns a Task (which should always be the case), you need to await it. This implicate that you have to mark your Method as async too. So your call should look like this:
txtIDDoc_Detail.Text = await ApiData.GetIdDoc();
The await waits till the long running Task is ready and returns it's inner value. All async Methods should return Task. If the Method is void it would be Task. Else it could be Task<int> or any other type. So await it and you can keep running ;)
#Sebi gives a great explanation of how to properly use async and await in this case, but I'm going to expand on exactly why you are getting the result that you see.
txtIDDoc_Detail.Text = ApiData.GetIdDoc().ToString()
Is returning
System.Threading.Tasks.Task`1[System.String]
Because you are calling .ToString on the instance of the Task Task(Of String), not the actual result. Types that don't override .ToString inherit the behavior of Object, which just returns the name of the type as a string.
You probably want this (asynchronous call):
txtIDDoc_Detail.Text = await ApiData.GetIdDoc()
Or this (synchronous call):
txtIDDoc_Detail.Text = ApiData.GetIdDoc().Result
Either of these calls will actually result of the task after it has completed.
Does the twilio asp.net helper library package NOT work in vb.net? I can get it to work in c# web app but not vb.net web app.
In a vb.net web application project the following code doesnt send an sms message and when stepping through with the debugger, errs on the send message line and brings up a file dialog asking for access to core.cs. The twilio library's were installed via nuget.
Public Shared Sub SendAuthCodeViaSms(ByVal number As String)
Dim twilioAccountInfo As Dictionary(Of String, String) = XmlParse.GetAccountInfoFromXmlFile("twilio")
Dim accountSid As String = twilioAccountInfo("username")
Dim authToken As String = twilioAccountInfo("password")
If (Not String.IsNullOrEmpty(accountSid) AndAlso Not String.IsNullOrEmpty(authToken)) Then
Dim client = New TwilioRestClient(accountSid, authToken)
client.SendMessage(TwilioSendNumber, ToNumber, "Testmessage from My Twilio number")
Else
'log error and alert developer
End If
End Sub
But in a C# web API project the same code sends the message as expected.
protected void Page_Load(object sender, EventArgs e)
{
const string AccountSid = "mysid";
const string AuthToken = "mytoken";
var twilio = new TwilioRestClient(AccountSid, AuthToken);
var message = twilio.SendMessage(TwilioSendNumber,ToNumber,"text message from twilio");
}
and all the sid's and tokens and phone number formats are correct, otherwise the c# one wouldnt send and I wouldnt get to the client.SendMessage part of vb.net version (client.SendSMSMessage produces the same result)
Twilio evangelist here.
I tried our your code by creating a simple VB console app and it worked for me.
The only thing I can think of is that either you are not getting your Twilio credentials correctly when parsing the XML, or the phone number you are passing into the function is not formatted correctly.
I'd suggest putting the result of call to SendMessage() into a variable and checking to see if RestException property is null:
Dim result = client.SendMessage(TwilioSendNumber, ToNumber, "Testmessage from My Twilio number")
If (Not IsNothing(result.RestException)) Then
' Something bad happened
Endif
If Twilio returns a status code greater than 400, then that will show up as an exception in the RestException property and will give you a clue as to whats going on.
If that does not work, you can always break out a tool like Fiddler to watch and see if the library is making the property HTTP request and Twilio is returning the proper result.
Hope that helps.
I couldn't find a full example for PostAsync so I had to piece one together. Therefore, I am not sure if what I am viewing is a limitation with the debugger or I simply did it wrong.
This is what I am trying to do:
I have to go through a list and make a web service call for each item on the list. My thought is that I could use the new 4.5 async stuff to keep it flowing without blocking during each call to the web service.
I've done a tone of research and watched Jon Skeet's video on TekPub, but I'm still not sure if I am doing this correctly. That is, when I set break points my async method never returns control to the caller. It basically seems to go along exactly as my synchronous version.
Question:
Is it normal for the debugger to appear synchronous or does that indicate my code is not implemented correctly?
Here is my Post method:
Public Async Function PostSecureXMLAsync(ByVal username As String, ByVal password As String, ByVal XMLtoSend As String) As Task(Of String)
Dim content = New StringContent(XMLtoSend, Encoding.UTF8, "text/xml")
Dim credentials = New NetworkCredential(username, password)
Dim handler = New HttpClientHandler() With {.Credentials = credentials}
Using client = New HttpClient(handler)
Using response = client.PostAsync(APIurl, content).Result
Return Await response.Content.ReadAsStringAsync()
End Using
End Using
End Function
This is how it is being used:
For Each ListItem In ListObj
...
Result = XMLExchangeObj.PostSecureXMLAsync(Username, Password, Payload).Result
...
Next
I was expecting control to return to the For Each loop while it was waiting for replies from the Web Service, but based on my break points it seems to be running synchronously.
When you're working with Async, you don't want to call Wait or Result. Instead, you should use Await. I see one Result in PostSecureXMLAsync:
Using client = New HttpClient(handler)
Using response = Await client.PostAsync(APIurl, content) ' Changed to Await
Return Await response.Content.ReadAsStringAsync()
End Using
End Using
And there's another one when you call your Async method:
Result = Await XMLExchangeObj.PostSecureXMLAsync(Username, Password, Payload)
This does mean that your calling method must also be Async, which means any methods that call that method should use Await, and must also be Async, etc. This "growth" through your code is perfectly normal. Just allow Async to grow until you reach a natural stopping point (usually an event handler, which you can make Async Sub).
I am very new to vb/.net and I'm trying to do something that I can do easily in classic vb. I want to get the source html for a webpage from the URL.
I'm using vb.net in Visual Studio Express for Windows 8.
I've read loads of stuff that talk about HttpWebRequest, but I can't get it to work properly.
I did at one point have it returning the html header, but I want to content of the page. Now, I can't even get it back to giving me the header. Ultimately, I want to process the html returned which I'll do (to begin with) the old-fashioned way and process the returned html as a string, but for now I'd like to just get the page.
The code I've got is:
Dim URL As String = "http://www.crayola.com/"
Dim request As System.Net.HttpWebRequest = System.Net.HttpWebRequest.Create(New Uri(URL))
txtHTML.Text = request.GetRequestStreamAsync().ToString()
Can anyone help me with an example to get me going please?
You're trying to use an Async method in a synchronous way, which won't make any sense. If you're using .NET 4.5, you can try marking the calling method with Async and then using the Await keyword when calling GetRequestStreamAsync.
Public Sub MyDownloaderMethod()
Dim URL As String = "http://www.crayola.com/"
Dim request As System.Net.HttpWebRequest
= System.Net.HttpWebRequest.Create(New Uri(URL))
' Use the Await keyword wait for the async task to complete.
Dim response = request.GetResponseAsync()
txtHTML.Text = response.GetResponseStream().ToString()
End Function
See the following MSDN article for more information on async programming with the Await keyword: http://msdn.microsoft.com/en-us/library/vstudio/hh191443.aspx
Edit
You are receiving your error because you're trying to get the Request stream (what you send the server), and what you really want is the Response stream (what the server sends back to you). I've updated my code to get the WebResponse from your WebRequest and then retrieve the stream from that.
Public Shared Function GetWebPageString(ByVal address As Uri) As String
Using client As New Net.WebClient()
Return client.DownloadString(address)
End Using
End Function
There is also DownloadStringAsync if you don't want to block
request.GetRequestStreamAsync() is probably not a method. I think you're cribbing code from a site where someone wrote their own add-on methods to HttpWebRequest. Try request.GetResponse() to return a response object, then in the response object you can inspect the stream and convert it to text if you need to.
This worked for me in VB.Net 4.5
Public Async Sub GetHTML()
Dim PageHTML as string
Dim client As New HttpClient
Dim getStringTask As Task(Of String) = client.GetStringAsync(PageURL)
PageHTML = Await getStringTask
MsgBox(PageHTML)
End Sub